甘孜黄土与青藏高原冰冻圈演化

Garz Loess and the Evolution of the Cryosphere on the Tibetan Plateau

逐样系统交变退磁磁性测量表明，８６ｍ的甘孜黄土剖面形成于约８１．８４×１０４ａＢＰ前。剖面中黄土石英砂类型分析揭示出至少约８１．８４×１０４ａＢＰ以前，高原已进入冰冻圈，并且很快于约７６×１０４ａＢＰ前冰川规模达到最大，并持续至约５３×１０４ａＢＰ前，倒数第二次冰期时冰川规模次之，然后冰川规模明显减少。同时揭示出大气环流和环境在约８１．８４×１０４，６０×１０４和１７．８×１０４ａＢＰ前发生过较明显的改变或调整与增强。

Magnetic polarity dating of a 86 m loess section at Garze on the southeastern Tibetan Plateau demonstrates that the bottom of the section was formed 818.4 ka BP. Analysis of various quartz sands in the section indicates that the plateau uplifted above snow line and began to develop glaciers at least 818.4 ka BP. ago. Soon late (c. 760 ka BP), glaciers reached their maximum, which are also largest in the scale during 818.4 ka BP., and may persist to about 530 ka BP. The second largest glaciation developed during the penultimate. Since the penultimate, the scale of glaciers has decreased greatly. The analysis also suggests that air circulation and environment occurred sharp changes or adjustments and enhancement at about 818.4 ka BP, 655 ka BP and 175 ka BP. They might be the results of accompanied environmental abrupt changes at some critical heights of the plateau with the sudden uplift.